1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor device without reworking and an apparatus for manufacturing a semiconductor device.
2. Description of the Related Art
A lithography step for a semiconductor integrated circuit comprises coating of a wafer with a photosensitive film and the following exposure of the photosensitive film, followed by its development. This lithography step requires a pattern in an upper layer to be aligned with a pattern in a lower layer before exposure is carried out using these patterns. FIG. 6 shows a flowchart of a conventional lithography step.
An alignment mark is provided on a semiconductor substrate for alignment with a pattern located above the substrate. A photosensitive film is formed on the semiconductor film (S201). In some cases, an antireflective film and a photosensitive film are sequentially formed on the semiconductor substrate (S202). Then, an exposure position, dose, and the height of the substrate are set (S203). An exposure device comprises an alignment mechanism that detects the position of a lower layer pattern. The alignment mechanism detects the position of an alignment mark arranged under the photosensitive film to calculate a position at which the photosensitive film is exposed using the pattern in the upper layer. Alignment is carried out on the basis of this positional information. Then, exposure is carried out using a device pattern (S204). The substrate is unloaded from the exposure device (S205). Then, the entire surface of the photosensitive film is subjected to PEB and development (S206) to form a photosensitive film pattern.
To increase an efficiency percentage, a misalignment inspection is carried out to check whether or not the photosensitive film pattern is aligned with a pattern formed in the underlying film (S207). For the misalignment inspection, an inspection device measures the positions of a misalignment inspection mark in the photosensitive film pattern and of a misalignment inspection mark formed in the underlying layer.
If the results of the inspection indicate that the magnitude of misalignment is out of an allowable range, the photosensitive film (in some cases, an antireflective film) is released (S208). Then, the exposure position, dose, and substrate height are corrected (S209). Subsequently, a process starting with the coating with a photosensitive film and ending with its development (S201 to S206), i.e. so-called reworking must be executed again. Reworking may have to cover the order of one lot. This increases the time required for manufacturing.
As described above, if the results of the misalignment inspection indicate that the magnitude of misalignment is out of the allowable range, reworking must be carried out. This increases manufacturing costs.